10,317 research outputs found
Study on Intumescent Flame Retarded Polystyrene Composites with Improved Flame Retardancy
The flame retardancy and thermal stability of ammonium polyphosphate/tripentaerythritol (APP/TPE) intumescent flame retarded polystyrene composites (PS/IFR) combined with organically-modified layered inorganic materials (montmorillonite clay and zirconium phosphate), nanofiber (multiwall carbon nanotubs), nanoparticle (Fe2O3) and nickel catalyst were evaluated by cone calorimetry, microscale combustion calorimetry (MCC) and thermogravimetric analysis (TGA). Cone calorimetry revealed that a small substitution of IFR by most of these fillers (≤2%) imparted substantial improvement in flammability performance. The montmorillonite clay exhibited the highest efficiency in reducing the peak heat release rate of PS/IFR composite, while zirconium phosphate modified with C21H26NClO3S exhibited a negative effect. The yield and thermal stability of the char obtained from TGA correlated well with the reduction in the peak heat release rate in the cone calorimeter. Since intumesence is a condensed-phase flame process, the MCC results showed features different from those obtained from the cone calorimeter
Synergistic Effect of Carbon Nanotubes and Decabromodiphenyl Oxide/Sb\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e in Improving the Flame Retardancy of Polystyrene
Brominated flame retardant polystyrene composites were prepared by melt blending polystyrene, decabromodiphenyl oxide, antimony oxide, multi-wall carbon nanotubes and montmorillonite clay. Synergy between carbon nanotubes and clay and the brominated fire retardant was studied by thermogravimetric analysis, microscale combustion calorimetry and cone calorimetry. Nanotubes are more efficient than clay in improving the flame retardancy of the materials and promoting carbonization in the polystyrene matrix. Comparison of the results from the microscale combustion calorimeter and the cone calorimeter indicate that the rate of change of the peak heat release rate reduction in the microscale combustion calorimeter was slower than that in the cone. Both heat release capacity and reduction in the peak heat release rate in the microscale combustion calorimeter are important for screening the flame retardant materials; they show good correlations with the cone parameters, peak heat release rate and total heat released
Lack of neurosteroid selectivity at δ vs. γ2-containing GABAA receptors in dentate granule neurons
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An Overview on STEM Education: Achievements and Challenges in the Age of Innovation
Science, Technology, Engineering, and Math (STEM) education has become increasingly important as the U.S. continues to grow and develop in the age of innovation. This article inventories the literature on the topic by exploring the current landscape of STEM education, achievements in the field, and challenges that stand in the wayEducatio
Branching ratios and direct CP asymmetries in decays
We propose a theoretical framework for analyzing two-body nonleptonic
meson decays, based on the factorization of short-distance (long-distance)
dynamics into Wilson coefficients (hadronic matrix elements of four-fermion
operators). The parametrization of hadronic matrix elements in terms of several
nonperturbative quantities is demonstrated for the decays,
denoting a pseudoscalar meson. We consider the evolution of Wilson coefficients
with energy release in individual decay modes, and the Glauber strong phase
associated with the pion in nonfactorizable annihilation amplitudes, that is
attributed to the unique role of the pion as a Nambu-Goldstone boson and a
quark-anti-quark bound state simultaneously. The above inputs improve the
global fit to the branching ratios involving the meson, and resolves
the long-standing puzzle from the and
branching ratios, respectively. Combining short-distance dynamics associated
with penguin operators and the hadronic parameters determined from the global
fit to branching ratios, we predict direct CP asymmetries, to which the quark
loops and the scalar penguin annihilation give dominant contributions. In
particular, we predict , lower than the LHCb and CDF data.Comment: 17 pages, 3 figures, matches published versio
Extracting CP violation and strong phase in D decays by using quantum correlations in psi(3770)-> D0\bar{D}0 -> (V1V2)(V3V4) and psi(3770)->D0\bar{D}0 -> (V1V2)(K pi)
The charm quark offers interesting opportunities to cross-check the mechanism
of CP violation precisely tested in the strange and beauty sectors. In this
paper, we exploit the angular and quantum correlations in the D\bar{D} pairs
produced through the decay of the psi(3770) resonance in a charm factory to
investigate CP-violation in two different ways. We build CP-violating
observables in psi(3770) -> D\bar{D} -> (V_1V_2)(V_3 V_4) to isolate specific
New Physics effects in the charm sector. We also consider the case of psi(3770)
-> D\bar{D} -> (V_1V_2)(K\pi) decays, which provide a new way to measure the
strong phase difference delta between Cabibbo-favored and doubly-Cabibbo
suppressed D decays required in the determination of the CKM angle gamma.
Neglecting the systematics, we give a first rough estimate of the sensitivities
of these measurements at BES-III with an integrated luminosity of 20 fb^-1 at
psi(3770) peak and at a future Super tau-charm factory with a luminosity of
10^35 cm^-2.s^-1.Comment: 13 pages
Bounds on convection driven by internal heating
Bounds are derived for the space–time averaged temperature 〈T〉〈T〉 of a fluid layer in the Boussinesq approximation between fixed-temperature horizontal boundaries subject to uniform heating HH throughout the volume. The analysis is carried out for both finite and infinite Prandtl number fluids. While the average temperature 〈T〉 ∼ H〈T〉∼H in the purely conductive state, convection enhances the heat transport beyond static conduction reducing the temperature. Lower bounds to the average temperature of the layer scale with the magnitude of the imposed heat flux, with one scaling exponent for the arbitrary Prandtl number case and another for the infinite Prandtl number model. Specifically, it is proven here that at large heating rates where convection is important, 〈T〉 ≥ c1H2/3〈T〉⩾c1H2/3 for finite Prandtl number fluids and 〈T〉 ≥ c2H5/7〈T〉⩾c2H5/7 for infinite Prandtl number fluids. Explicit prefactors c1c1 and c2c2 for the scaling bounds are computed as well. © 2004 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70833/2/JMAPAQ-45-7-2967-1.pd
Grenada’s Culture and Traditional Dress
Grenada is a Caribbean island that is located in the continent of South America. Grenada, also known as the ‘Spice Isle’ has a population of 105,897. It is divided into seven parishes – St. George’s being the capital. The country's main cultural traditions were handed down by African ancestors, however other ethnic groups such as Indians and Europeans also made contributions. Due to the large presence of Africans, their traditions were the most influential and present-day traditional dress and cultural practices reflect their elements. Key Words: Grenada Culture, Carnival, Grenada’s Traditional Wea
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